fee·ble-mind·ed (f??b?l-m?n?d?d)adj.1. Deficient in intelligence. No longer in scientific use.2. Exhibiting a marked lack of intelligent consideration and forethought: a feeble-minded plan doomed to failure.fee?ble-mind?ed·ly adv.fee?ble-mind?ed·ness n.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.